Wireless charging apparatus and method

ABSTRACT

Methods and apparatus for wireless charging are provided. Transmission power transmitted from a wireless power transmitter is received at a power receiver of a wireless power receiver. A battery of the wireless power receiver is charged with the received transmission power. It is determined whether the battery is fully charged. A packet from a communication unit of the wireless power receiver is transmitted to the wireless power transmitter when the battery is fully charged. An auxiliary charge of the battery is performed by receiving strength-reduced transmission power from the wireless power transmitter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/657,482, filed on Mar. 13, 2015, which is a continuation applicationof U.S. patent application Ser. No. 13/474,300, filed on May 17, 2012,now U.S. Pat. No. 9,000,723, which is based on and claims priority under35 U.S. § 119 to Korean Patent Application No. 10-2011-0046316, filed onMay 17, 2011 in the Korean Intellectual Property Office and to KoreanPatent Application No. 10-2012-0052123, filed on May 16, 2012 in theKorean Intellectual Property Office. The contents of each of theseapplications are incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a wireless charging apparatusand method, and more particularly, to a wireless charging apparatus andmethod that uses a wireless power receiver to wirelessly receive powerfrom a wireless power transmitter and that charges a battery with thereceived power.

2. Description of the Related Art

With the continued improvements in the field of Information Technology(IT) and the increasing prevalence of a wide variety of portableelectronic products, a variety of techniques have been developed thatsupply power for portable electronic products. Technology for supplyingpower typically used a power line in the past. However, wireless powertransmission technology, which is capable of wirelessly supplying power,has recently been developed.

Wireless power transmission technology includes technology fordelivering electrical energy in the form of electromagnetic waves,electromagnetic induction, or electromagnetic resonance, for example.Wireless power transmission technology makes it possible to supply powerwirelessly anytime and anywhere, without the use of power lines, suchas, electric wires. This wireless power transmission technology is acore technology for wirelessly charging electronic devices, supplyingwireless power for and/or wirelessly charging electric cars, supplyingwireless power to remote places, and supplying power to ubiquitouswireless sensors. Thus wireless power transmission technology hasattracted the attention of the public as a promising technology toreplace the existing schemes of supplying power for and/or chargingelectronic devices using electric wires.

For example, when wireless power transmission technology is used for awireless charging apparatus, the wireless charging apparatus may includea wireless power transmitter for supplying power, and a wireless powerreceiver for receiving power and charging its battery with the receivedpower. The wireless power transmitter may detect when an object is puton a source resonator by measuring a change in load or a change inresonant frequency from a wireless charging standby state. Upondetecting that the object is put on the source resonator, the wirelesspower transmitter determines whether the object is an object that mayundergo wireless charging, or whether the object is just a metallicobject, by performing an authentication process, such as, for example,exchanging an IDentifier (ID) with the object. If the authentication issuccessful, the wireless power transmitter starts negotiations on powertransmission, thereby determining that the object put on the sourceresonator is a wireless rechargeable-charger (e.g., a wireless powerreceiver). Upon completion of the negotiations, the wireless powertransmitter starts supplying wireless power for charging of the wirelesspower receiver so that the wireless power receiver may be charged. Thewireless power transmitter determines whether the wireless powerreceiver has been fully charged, and stops its power transmission to thewireless power receiver if the wireless power receiver has been fullycharged.

In the conventional wireless charging scheme described above, thewireless power transmitter stops its wireless power transmission whenthe wireless power receiver sends an End Power Transfer (EPT) packet tothe wireless power transmitter. Therefore, the wireless power receivermay not perform an auxiliary charge. The term ‘auxiliary charge’, asused herein, may refer to charging that is conducted to supplement thepower that has been self-discharged or consumed during use of thewireless power receiver with a full charge status displayed on UI.

Since the conventional wireless charging apparatus cannot perform anauxiliary charge, a User Interface (UI) screen may not display a fullcharge status with the transmission of wireless power interrupted.

Therefore, although the wireless charging apparatus has performedwireless charging for a long time, the user may misjudge that thewireless charging apparatus is out of order or malfunctions, because theuser can not perceive the full charge status on User Interface (UI)screen.

When the battery power of the wireless power receiver drops below apredetermined amount of power due to discharge while in the fullycharged state, the wireless power receiver performs recharging insteadof the auxiliary charge. During recharging, the wireless power receiverdisplays a charging status on the UI. Thus, the user may not be able todetermine whether the wireless power receiver is performing rechargingafter being fully charged, or the wireless power receiver is beingcontinuously charged before being fully charged. For example, the usermay misjudge that the wireless power receiver is being continuouslycharged without being fully charged, even though the wireless powerreceiver is actually being recharged after it was fully charged.

SUMMARY OF THE INVENTION

The present invention has been made to address at least the aboveproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the present inventionprovides a wireless power receiver that includes a communication unit, apower receiver configured to receive transmission power transmitted froma wireless power transmitter at a power receiver of the wireless powerreceiver, a battery configured to charge with the received transmissionpower, and a Power Management Integrated Circuit (PMIC) configured todetermine whether the battery is fully charged, to control thecommunication unit to transmit a Charge Status (CS) packet to thewireless power transmitter when the battery is fully charged and toperform an auxiliary charge of the battery by receiving strength-reducedtransmission power from the wireless power transmitter.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will be more apparent from the following detailed descriptionwhen taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a flow diagram illustrating a wireless charging operation of awireless charging apparatus that cannot perform an auxiliary charge;

FIG. 2 is a diagram illustrating a structure of a wireless chargingapparatus, according to an embodiment of the present invention;

FIG. 3 is a flow diagram illustrating a wireless charging method,according to an embodiment of the present invention; and

FIG. 4 is a diagram illustrating a structure of a Charge Status (CS)packet, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Embodiments of the present invention are described in detail withreference to the accompanying drawings. The same or similar componentsmay be designated by the same or similar reference numerals althoughthey are illustrated in different drawings. Detailed descriptions ofconstructions or processes known in the art may be omitted to avoidobscuring the subject matter of the present invention.

Embodiments of the present invention provide a wireless chargingapparatus and method for performing an auxiliary charge upon completionof wireless charging between a wireless power transmitter and a wirelesspower receiver. The wireless charging apparatus may be used forwirelessly charging electronic devices, supplying wireless power forand/or wirelessly charging electric cars, supplying wireless power toremote places, and supplying power to ubiquitous wireless sensors. Thewireless charging apparatus may be applied to any devices that canperform wireless power transmission and perform charging by receivingwireless power.

A wireless charging operation of a wireless charging apparatus thatcannot perform auxiliary charge is described in detail below.Thereafter, a wireless charging apparatus and method are described,which perform an auxiliary charge upon completion of wireless charging.

FIG. 1 is a flow diagram illustrating a wireless charging operationbetween a wireless power transmitter and a wireless power receiver, inwhich an auxiliary charge is not supported. Referring to FIG. 1, awireless power transmitter 10 charges, or recharges, a battery in awireless power receiver 50 by transmitting and receiving wireless power,in step 12.

In step 14, the wireless power receiver 50 determines whether it is in afully charged state in which its battery is fully charged. If thewireless power receiver 50 is in the fully charged state, the wirelesspower receiver 50 displays the full charge status indicating thatcharging of the wireless power receiver 50 is complete. The full chargestatus is displayed on a UI screen implemented by a display module, suchas a Liquid Crystal Display (LCD), so that a user of the wireless powerreceiver may recognize the fully charged state, in step 16.

In step 18, the wireless power receiver 50 transmits an End PowerTransfer (EPT) packet, having a Charge Complete message, to the wirelesspower transmitter 10 in accordance with the Wireless Power Consortium(WPC) 1.1 standard.

Upon receiving the EPT packet from the wireless power receiver 50, thewireless power transmitter 10 stops the transmission of wireless power,in step 20. While the wireless power receiver 50 receives no power, thefully charged battery is discharged little by little, and the fullcharge status will disappear from the UI screen.

In step 22, the wireless power receiver 50 determines whether thecharged power is less than or equal to a predetermined power due to theabove-described battery discharge. If the battery power is less than orequal to the predetermined power, the wireless power receiver 50 sends acharging request to the wireless power transmitter 10, in step 24.

In step 26, the wireless power transmitter 10 sends a response to thecharging request to the wireless power receiver 50. In step 28, uponreceiving the response to the charging request, the wireless powerreceiver 50 displays a charging status indicating that the wirelesspower receiver 50 is charging its battery. The charging status isdisplayed on the UI screen so that the user may recognize that thewireless power receiver 50 is charging its battery.

Thereafter, in step 30, the wireless power transmitter 10 charges thewireless power receiver 50 by transmitting and receiving wireless power.Steps 14 to 30 may be repeated until wireless powertransmission/reception is impossible due to, for example, separating thewireless power receiver 50 from the wireless power transmitter 10.

In the wireless charging apparatus and method described above, thewireless power transmitter 10 stops the transmission of wireless powerwhen the wireless power receiver 50 sends an EPT packet to the wirelesspower transmitter 10. Accordingly, the wireless power receiver 50 isprevented from performing an auxiliary charge.

Due to the inability of the wireless charging receiver 50 to perform theauxiliary charge, the wireless power receiver 50 doesn't display a fullcharge status with its charging interrupted. Thus, if the wireless powerreceiver 50 doesn't display a full charge status despite the lapse of afull charge time, the user may consider that the wireless chargingapparatus is out of order or malfunctions.

In addition, if the battery power is less than or equal to apredetermined power due to the discharge occurring in the fully chargedstate, the wireless power receiver 50 will perform recharging. Thewireless power receiver 50 displays a charging status on the UI. Theuser may not be able to determine whether the wireless power receiver 50is performing recharging after being fully charged, or the wirelesspower receiver 50 is being continuously charged before being fullycharged. For example, the user may misjudge that the wireless powerreceiver 50 is being continuously charged without being fully charged,even though it is actually being recharged after it was fully charged.

Accordingly, an embodiment of the present invention provides a wirelesscharging apparatus and method capable of performing an auxiliary chargeupon completion of the wireless charging between a wireless powertransmitter and a wireless power receiver.

FIG. 2 is a diagram illustrating s structure of a wireless chargingapparatus, according to an embodiment of the present invention.

Referring to FIG. 2, the wireless charging apparatus includes a wirelesspower transmitter 100 and a wireless power receiver 200.

The wireless power transmitter 100, which may be embodied as a chargingpad, for example, includes a power supply 110, a first controller 120, apower converter 130, a first coil 135, a first communication unit 140,and a first display 150.

The power supply 110, which is a power source, supplies necessary powerto the wireless power transmitter 100 and supplies Direct Current (DC)power for wireless power transmission.

The first controller 120, which controls the overall operation of thewireless power transmitter 100, generates various messages needed forwireless power transmission, sends the generated messages to the firstcommunication unit 140, receives messages from the first communicationunit 140, and performs control corresponding thereto. The firstcontroller 120 calculates an amount of transmission power based on theinformation received from the wireless power receiver 200, and controlsthe power converter 130 to convert the transmission power. If a CSpacket is received through the first communication unit 140 when abattery 240 in the wireless power receiver 200 is fully charged, thefirst controller 120 detects full charge status information included inthe CS packet. The CS packet includes information indicating a batterycharge level, and may have a value of 1 to 100. A value of 1 indicatesthat the battery 240 is almost completely uncharged, and a value of 100indicates that the battery 240 is fully charged. In the latter case,where the battery 240 in the wireless power receiver 200 is fullycharged, the wireless power receiver 200 may transmit a CS packet with avalue of 100. Upon receiving a CS packet indicating the full charge ofthe battery 240 in the wireless power receiver 200, the first controller120 controls the first display 150 to display full charge statusinformation thereon, and controls the power converter 130 to reduce astrength of the wireless power to a predetermined strength.

The power converter 130 converts a DC voltage provided from the powersupply 110 into transmission power so that the converted transmissionpower may be transmitted to the wireless power receiver 200 throughresonance by the first coil 135. The first coil 135 resonates at thesame frequency as that of a second coil 215 in the wireless powerreceiver 200 so that the transmission power may be transmitted to thewireless power receiver 200. If the wireless power receiver 200 is fullycharged, the power converter 130 reduces the strength of the wirelesspower (or the strength of transmission power) under control of the firstcontroller 120. The power converter 130 may reduce the strength of thetransmission power so that a predetermined voltage (e.g., 5V) may bemaintained, thereby also maintaining the power transmission.

The first communication unit 140 forwards a message (e.g., a CS packet)received from the wireless power receiver 200 to the first controller120. The first communication unit 140 also sends a message from thewireless power transmitter 100 to the wireless power receiver 200 undercontrol of the first controller 120.

The first display 150 may be a display module, such as, for example, aLight Emitting Diode (LED) or Liquid Crystal Display (LCD), whichdisplays full charge status information indicating that the wirelesspower receiver 200 has been fully charged, under control of the firstcontroller 120.

The wireless power receiver 200 charges its battery 240 with the powerwirelessly provided from the wireless power transmitter 100, configuredas described above. The wireless power receiver 200 may be embodied as amobile terminal, for example, and includes the second coil 215, a powerreceiver 210, a second controller 220, a Power Management IntegratedCircuit (PMIC, or power management chip) 230, the battery 240, a secondcommunication unit 250, and a second display 260.

If the second coil 215, a resonant coil, is aligned with the first coil135 in the wireless power transmitter 100, an induced current may occurin the second coil 215 due to changes in the magnetic field of the firstcoil 135. The second coil 215 resonates at the same frequency as that ofthe first coil 135 so that the wireless power may be received at thepower receiver 210.

The power receiver 210 receives the transmission power from the wirelesspower transmitter 100 through the second coil 215, and forwards thereceived power to the PMIC 230.

The second controller 220, which controls the overall operation of thewireless power receiver 200, generates various messages needed forwireless power reception, sends the generated messages to the secondcommunication unit 250, receives messages from the second communicationunit 250, and performs control corresponding thereto. The secondcontroller 220 controls the power receiver 210 to receive the powertransmitted from the wireless power transmitter 100, and controls thePMIC 230 so that the received power may be charged in the battery 240.The second controller 220 may receive a full charge message from thePMIC 230 when the battery 240 is fully charged. Upon receiving the fullcharge message, the second controller 220 controls the secondcommunication unit 250 to transmit a CS packet with a value of 100,which indicates that the battery 240 is fully charged. If the battery240 is fully charged, the second controller 220 controls the seconddisplay 260 to display the full charge status thereon.

The PMIC 230, a power management chip, charges the battery 240 with thepower that the power receiver 210 has received. The PMIC 230 monitorsthe current charge in the battery 240 and the voltage of the battery240. If the battery 240 arrives at a full charge condition, the PMIC 230performs an auxiliary charge while maintaining a jig-on voltage (avoltage fixedly provided to the PMIC 230 at 5V, and sends a full chargemessage to the second controller 220.

If the battery 240 is fully charged, the second communication unit 250transmits a CS packet to the wireless power transmitter 100, receives amessage from the wireless power transmitter 100, and forwards it to thesecond controller 220, under control of the second controller 220. TheCS packet includes information indicating a charge level of the battery240, and may have a value of 1 to 100, as described above.

The second display 260 may be embodied as a display module, such as, forexample, an LED or an LCD, and displays full charge status informationindicating that the battery 240 in the wireless power receiver 200 hasbeen fully charged, under control of the second controller 220.

In the wireless charging apparatus described in the embodiment of thepresent invention above, if the battery 240 in the wireless powerreceiver 200 is fully charged, the wireless power receiver 200 sends aCS packet, instead of an EPT packet, to the wireless power transmitter100. Accordingly, an auxiliary charge is performed so that the powertransmitted from the wireless power transmitter 100 is continuouslytransmitted after being reduced, without being interrupted. Thisprevents the repeated charging and recharging of the battery 240.

FIG. 3 is a flow diagram illustrating a wireless charging method,according to an embodiment of the present invention.

Referring to FIG. 3, in step 302, the wireless power transmitter 100 andthe wireless power receiver 200 charge the battery 240 in the wirelesspower receiver 200 by transmitting and receiving wireless power.

In step 304, the wireless power receiver 200 determines whether it is ina fully charged state, in which battery charging has been completed. Ifthe wireless power receiver 200 is in the fully charged state, thewireless power receiver 200 displays a full charge status, indicatingthe completed charging of the wireless power receiver 200, on a UIscreen of the second display 260, implemented by a display module suchas LCD, in step 306.

In step 308, the wireless power receiver 200 transmits a CS packet tothe wireless power transmitter 100. The CS packet includes informationindicating a charge level of the battery 240, and may have a value of 1to 100, as described above.

FIG. 4 is a diagram illustrating a structure of a CS packet, accordingto an embodiment of the present invention.

Referring to FIG. 4, for the CS packet, a CS packet type defined in theWPC 1.1 standard may be used. B0 represents one byte, which may include8 bits of b7˜b0. In an embodiment of the present invention, if thebattery 240 is fully charged, a CS Value may be 0×63 to indicate a valueof 100.

Upon receiving the CS packet from the wireless power receiver 200, thewireless power transmitter 100 displays full charge status informationon the first display 150 in step 310. The wireless power transmitter 100reduces transmission strength of the wireless power while maintainingthe wireless power transmission without interruption, in step 312.

In step 314, the wireless power receiver 200 receives the reducedwireless power from the wireless power transmitter 100 and keeps apredetermined fixed voltage, thereby performing an auxiliary charge.

As is apparent from the foregoing description, the wireless chargingapparatus and method of embodiments of the present invention enable anauxiliary charge upon completion of wireless charging between thewireless power transmitter and the wireless power receiver, making itpossible for the user to identify the exact full charge statusinformation in the fully charged state. By enabling the auxiliary chargeupon completion of the wireless charging between the wireless powertransmitter and the wireless power receiver, it is possible that eventhough the battery is recharged due to the discharge after it was fullycharged, the user may not recognize this situation.

While the invention has been shown and described with reference tocertain embodiments thereof, it will be understood by those skilled inthe art that various changes in form and detail may be made thereinwithout departing from the spirit and scope of the invention as definedby the appended claims and their equivalents.

What is claimed is: 1: An electronic device comprising: a battery; acommunication circuit; a power receiving circuit for generating acurrent based on an electromagnetic field provided from a wireless powertransmitting device; and controlling circuitry configured to at least:control to charge the battery using a first current generated at thepower receiving circuit based on an electromagnetic field with a firststrength provided from the wireless power transmitting device, based ona full charge condition for the battery being satisfied, control totransmit, through the communication circuit, first information towardsthe wireless power transmitting device, the first information comprisinga charging status of the battery of the electronic device, and after thefirst information is transmitted, control to charge the battery using asecond current generated at the power receiving circuit based on theelectromagnetic field with the second strength provided from thewireless power transmitting device, to maintain the full chargecondition for the battery. 2: The electronic device of claim 1, whereinthe first information comprises a charge status (CS) packet, and whereinthe CS packet is based on a Wireless Power Consortium (WPC) standard. 3:The electronic device of claim 2, wherein the CS packet comprises acharge level having a value between 1 and 100, and wherein the CS packethas a value of 0×63 indicating a value of 100 when the full chargecondition for the battery is satisfied. 4: The electronic device ofclaim 1, wherein the controlling circuitry is further configured tocontrol to display, on a display of the electronic device, full chargestatus information for the battery based on the full charge conditionfor the battery being satisfied. 5: The electronic device of claim 4,wherein the controlling circuitry is further configured to control todisplay, on the display of the electronic device, charging statusinformation indicating the battery is charging, while the battery isbeing charged with the first current. 6: The electronic device of claim1, wherein the controlling circuitry is further configured to: control aPower Management Integrated Circuit (PMIC) of the electronic device tocharge the battery using the first current or the second current, andcontrol to receive from the PMIC second information indicating the fullcharge condition for the battery is satisfied, wherein the firstinformation is based on the second information. 7: The electronic deviceof claim 1, wherein the controlling circuitry is further configured tocontrol to charge using the second current by continuously charging thebattery using the second current after the first information istransmitted, to maintain the full charge condition for the battery. 8:The electronic device of claim 1, wherein the power receiving deviceincludes a first coil for generating the first current and the secondcurrent, and for transmitting the first information. 9: A method ofcharging a battery for an electronic device, comprising: charging thebattery using a first current generated at a power receiving circuit ofthe electronic device based on an electromagnetic field with a firststrength provided from a wireless power transmitting device; based on afull charge condition for the battery being satisfied, transmitting,through a communication circuit of the electronic device, firstinformation towards the wireless power transmitting device, the firstinformation comprising a charging status of the battery of theelectronic device; and after the first information is transmitted,charging the battery using a second current generated at the powerreceiving circuit based on an electromagnetic field with a secondstrength provided from the wireless power transmitting device, tomaintain the full charge condition for the battery. 10: The method ofclaim 9, further comprising displaying, on a display of the electronicdevice, full charge status information indicating that the full chargecondition for the battery is satisfied. 11: The method of claim 10,further comprising displaying, on the display of the electronic device,charging status information indicating the battery is charging, whilethe battery is being charged using the first current. 12: The method ofclaim 9, further comprising obtaining, from a Power ManagementIntegrated Circuit (PMIC), second information indicating that the fullcharge condition for the battery is satisfied, wherein the firstinformation is based on the second information. 13: The method of claim9, wherein the charging the battery using the second current comprisescontinuously charging the battery using the second current after thefirst information is transmitted, to maintain the full charge conditionfor the battery.